The present invention relates in general to apparatus for testing electrical components, and more particularly to apparatus for testing electrical components which control the flow of fluid under pressure and for testing electrical components which are operatively responsive to fluid pressures.
Automotive transmissions include switches operatively responsive to hydraulic fluid pressures. The switches open and close at various predetermined hydraulic fluid pressures. During the change of gears and during speed variations in the automotive transmission, the hydraulic fluid pressure within the transmission changes and the switches, respectively, open and close in response to the hydraulic fluid pressure. Automotive transmissions also include solenoid valves. The energization and deenergization of the solenoid valves control the flow of fluid under pressure in the automotive transmission.
Heretofore, rebuilders of automotive transmissions tested the electrical switches operatively responsive to hydraulic fluid pressures for basic ON/OFF functions by measuring the conductance of the switches while subjecting the switches to unmetered air pressure. This arrangement was not satisfactory, since it failed to take into consideration that the electrical switches are calibrated to open and close within prescribed ranges of fluid pressure.
The U.S. patent to Ayoub et al., U.S. Pat. No. 4,356,724, issued on Nov. 2, 1982, for Apparatus and Method For Testing Transmissions, discloses an apparatus for testing automotive vehicular transmissions in which the output of the transmission under test is operatively connected to a load device. The load device provides a loading torque to the output shaft. During the test procedure, the torque converter is rotated at varying speeds while a loading torque is imparted to the output shaft. A vacuum is supplied to the vacuum modulator control of the transmission under test, and the hydraulic pressure of the transmission under test is monitored. A microcomputer controls and monitors the test procedure to determine whether the transmission upshifted or downshifted within predetermined limits.
In the U.S. patent to Wesner et al., U.S. Pat. No. 3,967,495, issued on July 6, 1976, for Instrument For Testing A Pneumatic Control System Of A Vehicle Transmission, there is disclosed a diagnostic instrument which detects and locates malfunctions in a pneumatic circuit that controls a transmission in response to the movement of an operator's shift lever. Connectors enable the coupling of pneumatic signal lever with various flow paths of the transmission control circuit. The presence or absence of pressure at various points in the control circuit is determined. Compressed air is directed to selected circuit flow paths through the test instrument and gauges in the instrument determine the magnitude of the pressure at selected points in the control circuit.
In the U.S. patent to Rau, U.S. Pat. No. 3,389,600, issued on June 25, 1968, for Fluid Pressure Testing Apparatus For Automatic Vehicle Transmission, there is disclosed apparatus for diagnosing malfunctions in the hydraulic systems in the automatic transmissions of automotive vehicles. The apparatus includes insert means communicating with gauges which indicate operating characteristics of different fluid circuits and fluid pressure control elements of the transmission.
The U.S. patent to Williams, U.S. Pat. No. 3,145,560, issued on Aug, 25, 1964, for Testing Means For Automotive Equipment, discloses an adapter for testing the operation of an automotive automatic transmission. Nozzles apply air under pressure to the open end of passages in the automatic transmission. The application of air under pressure causes elements of the transmission with which the passages communicate to operate. In this manner, the elements can be inspected.